The revolutionary Bacillus thuringiensis (Bt) cotton crop in India has started losing steam steadily due to lack of innovation and diversified pest attacks emerging from frequent changes in climatic conditions.

As is evident from the data collated by the Cotton Advisory Board (CAB) under the Union Ministry of Textiles, cotton yield has started falling gradually after the four years of revolution between 2002 and 2006 when bollworm-resistant Bt cotton seed changed farmers’ economy. After that, however, farmers have witnessed a sustained decline in yield from a peak level of 554.39 kg per hectare (ha) in the cotton year 2006-07 (October – September) to an estimated 488.89 kg per ha in 2012-13.

The remarkable increase in output, therefore, is attributed to farmers’ rapid adoption of Bt technology resulting in higher acreage. The fall in area under cultivation resulted in lower cotton output in the past few years.

Although, the innovator of Bt technology, the US-headquartered Monsanto claims to have introduced an update of bollworm resistant Bt cotton, the technology failed to help raise India’s per hectare yield.

“The average Bt cotton yield declines are possibly due to the expansion of the crop to non-optimal areas of cultivation. In addition, yield losses due to other factors, including sucking pests, have also made an impact in the past few years,” said Raju Barwale, managing director, Maharashtra Hybrid Seeds Company (Mahyco), an agri-biotechnology company and an associate of the Indian arm of Monsanto.

However, India’s current average cotton productivity is 474 kg/ha for the post-Bt cotton launch period 2002-11, an increase of 158 per cent from pre-Bt cotton period of 1993-2001 when productivity was 300 kg/ha.

Barwale said the estimated yield of cotton during kharif 2012 was lower due to the drought in major growing areas, such as Saurashtra, Vidarbha and North Karnataka. The drought impacted yields of other crops in these regions as well.

Bt technology is intended to protect the cotton crop against bollworm attacks, thereby helping to minimise insect-related crop losses. Bt cotton’s resistance towards bollworms remains intact with Bollgard II technology. There is no scientific evidence indicating resistance being developed by the insect to Bollgard II cotton.

“During field monitoring of the cotton crop in 2009 in Gujarat, Monsanto and Mahyco scientists detected unusual survival of the pink bollworm (PBW) to the first-generation single-protein bollgard cotton. Laboratory testing confirmed resistance in PBW populations to Bt protein in bollgard cotton in Gujarat. This was reported to the Indian Genetic Engineering Approval Committee (GEAC). However, the second-generation Bt cotton containing two Bt proteins (Bollgard IITM) continued to be effective in controlling pink bollworms and the resistance issue could be quickly overcome with adoption of Bollgard II,” a Monsanto India spokesperson said.

Resistance is natural and expected, so measures to delay resistance are important. Among the factors that may have contributed to pink bollworm resistance to the Cry1Ac protein in Gujarat are limited refuge planting and early use of unapproved Bt cotton seed, planted prior to GEAC approval of Cry1Ac cotton, which may have had lower Bt protein expression levels, he added.

Meanwhile, Barwale pointed out that crop yield depends on many other factors, including availability of water, nutrients, soil fertility, agronomic practices, regular and efficient management of weeds, insect protection and labour.

There is a growing need and significant opportunity ahead. With increasing population and income and the textile industry’s vision to triple in value by 2020, it is important for farmers to increase their cotton production. Safe and proven technology such as GM crops and Bt cotton will play an important role in enhancing yield and profitability at their farms.

Both Monsanto and Mahyco have defended the new technology - Bollgard II - which they claim have capability to resist PWB.

Monsanto advised farmers to regularly monitor the fields under Bt cotton cultivation. Planting non-Bt cotton refuge is the most important practice the farmers should adopt.

Furthermore, farmers have been constantly educated to adopt measures such as need-based application of insecticide sprays during the crop season and adoption of cultural practices like keeping the field clean of cotton stubble and crop-leftovers, ploughing of land after harvest so that the resting stages of the insects in the soil could be destroyed.

Meanwhile, continuous R&D and innovation to develop new value-added technologies is imperative to stay ahead of insect resistance. To support such innovation, Monsanto demanded government policies’ support to encourage investment in R&D which will result in Indian farmers having a wider choice of better and advanced technologies translating thereby, higher yield.